Bewilderment... and then Indifference
Antichamber is a very unique experience. It's designed from the get-go to completely decimate your expectations, and it succeeds at that in more than one way. Your preconceptions of space (or what the definition of the word "room" is,) can get you into a lot of trouble in this game. You may find yourself in three different areas before you complete a full 360º turn. Additionally, walls, floors, and ceilings may dissolve to show you the true nature of things, or a furious atom may get incredibly disturbed by even the slightest of your movements. These are all elements that I love about Antichamber. It's strange, makes no excuses, and succeeds at somehow being an entirely engrossing and unified experience. This world has laws, weird ones, that are never altered or changed, and it uses these laws to create solid, mind-bending puzzles.
However, there are a few times where the puzzles are unfair. For instance, you get a tool that is used to absorb and place blocks. You are always limited by the amount of block-material you find in the environment... at least at first. Now, this tool is upgraded a number of times through-out the game, and sometimes you find yourself (particularly early on in the game,) unaware if you need an upgrade, or if a puzzle is solvable right then and there. There was one puzzle in particular, approximately an hour into the game, where I had a sneaking suspicion that what I was attempting was actually impossible. I was right, with no indication that there was further equipment to be had, it was a very frustrating thirty minutes as I tried my best to solve this impossible problem. This isn't that big of a deal, but couple that with the blinding visuals, and the strange, incomplete things here and there, and Antichamber straight-up loses a star. However, the game is more often-than-not genuinely clever, so it isn't that bad.
If you're in the market for a decent puzzle game that'll kill an afternoon or two, then Antichamber is a good choice. The nature of the environment and the incredibly skilled level design makes for interesting puzzles, an interesting concept, and an overall entertaining experience.